bktemp,
yes that might be the case.
The OKI C1162 I replaced, shorted the high voltage to nearly zero.
But with the chip still in place I measured the other voltages and they were just fine.
The inverter got a little warm (not hot) and also the defective OKI had some temperature.
After replacing the OKI all the voltages are within expected ranges.
And the 8052 controller seems to work, because the plotter recognizes the display and starts up fine.
It's just, the controller doesen't output anything to the display side.
Of course I also would replace the 8052, but at the moment I have noreplacement handy.
I think I'll desolder the thing and try to read out the ROM contents. Hope that is still possible.
Atmel produced a AT89C52, which is compatible, but comes with a flash on chip. This will replace the 8052 just fine.
The thing is, I'm fed up with this non-reliable VFD board and would really like to replace it with a common LCD.
It's the second time now the thing breaks!
Also it was already very pale before the OKI chip died.
Is there a way to refresh faded VFDs, btw?
Lothar
D'oh!
I just read the 8052 has a security bit that prevents readout of the ROM if set, which it most likely is.
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif.pagespeed.ce.8iLbFYV4Bc.gif)